Head of House: Professor Snape

'-and then she... she... didn't even get in trouble for it! Waaaah! It's not fair!!! ...Hey! Are you asleep?'
'...No, I'm not that lucky. Look, it's not supposed to be fair.'
'Eh? But what are you going to do?'
'Nothing. You're going to exact brutal revenge.'
'...Me?'
'You sorted into Slytherin, didn't you.'
'....Uh. Yes. ...I'm allowed?'
'If you cause death or permanant injury of any sort, I'll expell you and send you to Azkaban myself. If you get caught, you'll get detention and points off. Otherwise, have fun. Fill her ink bottles with cat urine, punch holes in her wellies, put spiders in her sock drawer, whatever. As long as I don't hear about it, I don't care.'
'Really! Oh, boy!'
'Go away, kid. You're bothering me.'
'Eehehehehe! Bye!'